The present invention relates to construction of an overhead bi-fold door.
Overhead bi-fold doors are known for use in large buildings in which high clearances, wide spans and simple construction are desirable. Known types of overhead bi-fold doors commonly have a large frame including numerous frame members required for strength. Cladding is typically supported on an outer side of the door with insulation accordingly being provided against an inner side of the door. Due to the irregular surface of the beams forming the frame of the door along the inner side of the door, insulation is typically provided in panels which fit between the beams resulting in thermal leakage at the beams thus reducing the insulating value of the entire door.
According to the present invention there is provided an overhead bi-fold door construction comprising a door member and mounting means for supporting the door member on a building, the door member comprising:
a top beam extending along a top end of the door member;
a bottom beam extending along a bottom end of the door member;
two side beams extending along opposing sides of the door member;
a hinged seam extending across the door member partway between the top and bottom beams of the door member and dividing each side beam into a respective upper section and a respective lower section;
the door member being separated by the hinged seam into an upper panel including the top beam and the upper sections of the side beams and a lower panel including the bottom beam and the lower sections of the side beams;
the upper and lower sections of the side beams being foldable relative to one another at the hinged seam between a closed position of the door member in which the upper and lower sections lie in a generally common upright plane and an open position of the door member in which the bottom beam is raised upwardly towards the top beam in relation to the closed position;
an upper frame spanning the upper sections of side beams;
a lower frame spanning the lower sections of the side beams;
an outer surface of the upper and lower frames being recessed in relation to an outer surface of at least one of the top beam, the bottom beam and the side beams;
sheeted insulation material being supported on the outer surface of the upper and lower frame; and
cladding being supported on an outer side of the sheeted insulation material.
The use of insulation between the frame of the door and the cladding permits a continuous layer of insulation of substantially constant thickness to be provided. This minimizes thermal losses through the door. Furthermore a neater appearance results while permitting thicker beams to be used for additional strength along the top, bottom or sides of the door and optionally along the central hinged seam as well.
The outer surface of the upper frame is also preferably recessed in relation to an outer surface of both the bottom beam and the top beam, in addition to the outer surface of the side members.
In this arrangement, the outer surfaces of the top beam, the bottom beam and the respective sections of the side beams are preferably all substantially flush with one another.
The outer side of the sheeted insulation material may thus be arranged to lie flush with the outer surfaces of the top,beam, the bottom beam and the side beams.
The cladding preferably overlaps the outer side of the sheeted insulation material and the outer surfaces of the top beam, the bottom beam and the side beams.
Preferably, the sheeted insulation material spans the door member substantially uninterrupted at a substantially constant thickness between the side beams and between the top and bottom beams.
The sheeted insulation material may be divided at the hinged seam in a manner so as to define a pair of abutting surfaces of the sheeted material in the closed position of the door member in which the abutting surfaces are preferably capped by a suitable cladding material.
Each of the upper and lower frames may include a cross beam extending along the hinged seam having an outer surface which is recessed in relation to the side beams. In this instance, the sheeted material preferably extends between the cross beams and the cladding.
Each of the upper and lower frames may additionally include a layer of inner sheeted material spanning the side beams between the respective frame and the sheeted insulation material.